The present invention relates to a pressure control valve for regulating the pressure in a conduit depending on the magnitude of a control pressure. The invention further relates to a pressure control valve which employs a non-elastically deformable diaphragm disposed within a pressure cell and defining two opposite chambers. One of the chambers contains a valve assembly with a seat which is opened and closed by a movable member attached to the diaphragm.
It is the purpose of the pressure control valves of this type to adjust the pressure in a flowing gaseous medium to a constant value or to the magnitude of a control pressure. Such valves are required when it is necessary to measure the flow rate of gases by permitting their flow from a high pressure level to a lower pressure. Known in the art are pressure control valves which employ soft yieldable diaphragms which are biased by one or several springs. The disadvantage of such valves is that the difference between the control pressure and the desired adjusted pressure is thus dependent on the excursion of the diaphragm which can be substantial in certain applications.